The present disclosure relates to a liquid crystal display including a liquid crystal display element in which a liquid crystal layer is sealed between a pair of substrates including alignment films on facing surfaces thereof.
In recent years, a liquid crystal display (LCD) has been widely used as a display device of a liquid crystal television receiver, a note-type personal computer, or a car navigation device. This liquid crystal display is classified in various display modes (methods) depending on molecular arrangement (alignment) of liquid crystal molecules contained in a liquid crystal layer interposed between substrates. A twisted nematic (TN) mode in which the liquid crystal molecules are twisted and aligned in a state where voltage is not applied, is well known as the display mode, for example. In the TN mode, the liquid crystal molecules has positive dielectric anisotropy, that is, a property for obtaining a greater dielectric constant of the liquid molecules in a long axis direction compared to that in a short axis direction. Accordingly, the liquid crystal molecules have a structure of sequentially rotating alignment azimuths of the liquid crystal molecules and aligning the alignment azimuths in a direction perpendicular to substrate surfaces, in a surface parallel with the substrate surfaces.
Meanwhile, attention is paid to a vertical alignment (VA) mode in which the liquid molecules are aligned to be perpendicular to the substrate surfaces in a state where voltage is not applied. In the VA mode, the liquid crystal molecules have negative dielectric anisotropy, that is, a property for obtaining a smaller dielectric constant of the liquid molecules in a long axis direction compared to that in a short axis direction, and a viewing angle which is wider than that in the TN mode can be realized.
The liquid crystal display in the VA mode has a configuration in that, if voltage is applied thereto, the liquid crystal molecules aligned in a direction perpendicular to the substrates respond so as to be tilted in a direction parallel to the substrates by the negative dielectric anisotropy to allow light to transmit therethrough. However, since the direction in which the liquid crystal molecules aligned in the direction perpendicular to the substrates are tilted, is arbitrary, the alignment of the liquid crystal molecules is disordered due to voltage application, and accordingly response characteristics with respect to the voltage are degraded.
Herein, a technology of regulating the direction in which the liquid crystal molecules are tilted by responding to the voltage is reviewed in order to improve the response characteristics. In detail, for example, Japanese Unexamined Patent Application Publication No. 2011-095696 discloses a liquid crystal display including a liquid crystal display element including a pair of alignment films which are provided on facing surfaces of a pair of substrates, and a liquid crystal layer which is provided between the pair of alignment films and includes liquid crystal molecules having negative dielectric anisotropy, in which at least one of the pair of alignment films contains a compound obtained by crosslinking polymer compounds each including a crosslinkable functional group as a side chain, with each other, and pretilt is applied to the liquid crystal molecules by the crosslinked compound. The technology disclosed in Japanese Unexamined Patent Application Publication No. 2011-095696 is also called a field-induced photo-reactive alignment (FPA) method.
Meanwhile, a technology of using a liquid crystal composition including an alkenyl compound is reviewed in order to realizing high-speed response (for example, see Japanese Unexamined Patent Application Publication No. 2009-149667 and Japanese Unexamined Patent Application Publication No. 2008-106280). By containing the alkenyl compound in the liquid crystal composition, viscosity of the liquid crystal composition is decreased, and accordingly it is possible to realize high-speed response of the liquid crystal display.